In Daoism the quest for immortality is extremely varied and so quite difficult to define; however, a significant factor in immortality is that other people recognize you have become an immortal at the time of your death or sometime after your death. The so called "highest" way to demonstrate becoming an immortal at the moment of death is to "Rise up in broad daylight with your dogs and chicken." Zhang Daoling (the founder of Religious Daoism) did this, as did his wife, his 3 sons and their wives.
Dao Hongjing and Ge Hong, the two most famous alchemists, became immortals simply by hiring a carriage (you know, a taxi) taking a trip out into the wilderness and then "Sending the Carriage Back Empty." There are hundreds of unique (loosely) documented ways of demonstrating the transition to being an immortal. Often when Chinese people died they were put into big ceramic jars in a squatting position. Then, after their skin and organs had fully decomposed their bones were transfered to a smaller jar. It turns out that some immortals were recognized during this transfer of bones because Daoist sacred texts (like the Daodejing for instance) were written on their bones!
You can tell an enormous amount about how someone lived by studying their bones. The shape, density, places of wear, and chemical composition of a persons bones tell a real story. This is the premise of the wonderful Fox T.V. show Bones where a forensic anthropologist and an FBI agent team up to solve crimes by looking at bones. Since my sister is an Archaeologist I sometimes call her up after watching the show to find out if what they did on the show could really happen. Often it can! My sister says she can often tell what kinds of work a person did, or what kind of weapons a person used by looking at their bones.
This got me thinking. It must be possible to tell what kind of martial arts a person was doing by looking at their bones. I want to know if there are people with Taijiquan type bones or Shaolin type bones a thousand years ago. This could be done, and eventually it could be done so well that we could see the entire history of martial arts by region over 3 thousand years!!!
So little is known about our physiology. It is hard to put a percentage on, but if we know more than 10% of what there is to know about physiology I would be surprised. Here is some very cool new research about bones, here too.
...(N)ew research shows that bones release a protein called osteocalcin involved in controlling sugar and fat absorption, thus acting like a hormone....
"Because osteocalcin is secreted by one organ and acts on others, it fits the definition of a hormone, making bones part of the endocrine system..."
What do you have written on your bones?